Kev sib tsoo thiab kev txuag lub zog tshuab - cov khoom soj ntsuam thiab cov kev daws teeb meem
1. Ob yam khoom muaj tib lub cev hnyav , m1 = m2 = 0.5 kg poob ntawm tib qhov siab raws li pom hauv daim duab hauv qab no. Lub vojvoog ntawm lub voj voog yog 1/5 m. Kev sib tsoo ntawm ob yam khoom yog elastic zoo meej. Txheeb xyuas qhov ceev ntawm txhua yam khoom tom qab kev sib tsoo. Kev nrawm vim lub ntiajteb txawj nqus yog 10 m/ s2.
Paub:
Qhov hnyav ntawm yam khoom (m) = m1 = kuv2 = 0.5 kg
Qhov siab pib (h 1 ) = 1/5 m
Qhov siab kawg (h 2 ) = 0 ( lub hauv paus ntawm txoj kev )
Qhov ceev pib ntawm yam khoom (v 1 ) = 0 ( yam khoom thaum pib so )
Qhov ceev kawg ntawm yam khoom (v 2 ) = .... ( qhov ceev ntawm yam khoom ntawm lub hauv paus ntawm txoj kev = qhov ceev ntawm yam khoom ua ntej sib tsoo )
Kev nrawm vim lub ntiajteb txawj nqus (g) = 10 m/s
Xav tau: Qhov ceev ntawm txhua yam khoom tom qab sib tsoo
Tshuaj:
Qhov ceev ntawm cov khoom ua ntej kev sib tsoo
Qhov ceev ntawm yam khoom ua ntej sib tsoo = qhov ceev ntawm yam khoom thaum tuaj txog ntawm lub hauv paus ntawm txoj kev = qhov ceev kawg ntawm yam khoom.
Lub zog kho tshuab pib = lub zog kho tshuab kawg
Lub zog gravitational potential + kinetic energy = lub zog gravitational potential + kinetic energy
mgh 1 + 1/2 mv 1 2 = mgh 2 + 1/2 mv 2 2
mgh 1 + 0 = 0 + 1/2 mv 2 2
mgh 1 = 1/2 mv 2 2
gh 1 = 1/2 v 2 2
2 gh 1 = v 2 2
2(10)(1/5) = v 2 2
2(2) = v 2 2
4 = v 2 2
v2 = √4
v2 = 2 m/ s
Qhov ceev ntawm txhua yam khoom ua ntej sib tsoo yog 2 m//s.
Qhov ceev ntawm cov khoom tom qab sib tsoo
Yog tias ob yam khoom muaj tib lub cev hnyav thiab txav mus rau hauv qhov sib txawv ces thaum lawv sib tsoo, ob yam khoom hloov lawv qhov ceev. Piv txwv li, yog tias ua ntej sib tsoo khoom A txav ntawm 2 m/s thiab khoom B txav ntawm -4 m/s, tom qab sib tsoo khoom A txav ntawm 4 m/s thiab khoom B txav -2 m/s. Cov cim rho tawm thiab ntxiv qhia tias ob yam khoom muaj qhov sib txawv.
2. Qhov hnyav ntawm yam khoom A yog 2-kg thiab qhov hnyav ntawm yam khoom B yog 3 kg poob ntawm qhov siab raws li pom hauv daim duab hauv qab no. Ob yam khoom sib tsoo ntawm qhov chaw C. Qhov kev sib tsoo yog elastic zoo heev. Kev nrawm vim lub ntiajteb txawj nqus yog 10 m/s 2. Txheeb xyuas qhov ceev ntawm yam khoom A thiab qhov ceev ntawm yam khoom B tom qab kev sib tsoo.
Paub:
Qhov hnyav ntawm yam khoom A (m1) = 2 kg
Qhov hnyav ntawm yam khoom B (m2 ) = 3 kg
Qhov siab pib (h 1 ) = 5 meters
Qhov siab kawg (h 2 ) = 0 ( lub hauv paus ntawm txoj kev )
Qhov ceev pib ntawm yam khoom (v 1 ) = 0 ( thaum pib yam khoom so )
Qhov ceev kawg ntawm yam khoom (v 2 ) = .... ( qhov ceev ntawm lub hauv paus ntawm txoj kev = qhov ceev ua ntej sib tsoo )
Kev nrawm vim lub ntiajteb txawj nqus (g) = 10 m/s
Xav tau: Qhov ceev ntawm txhua yam khoom tom qab sib tsoo
Tshuaj:
Qhov ceev ntawm cov khoom ua ntej kev sib tsoo
Qhov ceev ntawm yam khoom ua ntej sib tsoo = qhov ceev ntawm yam khoom ntawm lub hauv paus ntawm txoj kev
Lub zog tshuab pib = lub zog tshuab kawg
Lub zog gravitational potential = kinetic energy
mgh 1 = 1/2 mv 2 2
gh 1 = 1/2 v 2 2
2 gh 1 = v 2 2
2(10)(5) = v 2 2
100 = v2 2
v2 = √100
v2 = 10 m/ s
Qhov ceev ntawm txhua yam khoom ua ntej sib tsoo = 10 m/s.
Qhov ceev ntawm cov khoom tom qab sib tsoo
Ob yam khoom muaj qhov hnyav sib txawv thiab txav mus rau hauv cov kev taw qhia sib txawv yog li qhov ceev ntawm txhua yam khoom tom qab sib tsoo raug suav los ntawm kev siv kab zauv no.
Qhov ceev ntawm txhua yam khoom tom qab kev sib tsoo:
- Qhov txawv ntawm kev sib tsoo elastic thiab kev sib tsoo inelastic yog dab tsi?
- teb: Hauv kev sib tsoo uas ywj pheej, ob qho tib si lub zog kinetic thiab momentum raug khaws cia. Hauv kev sib tsoo tsis ywj pheej, momentum raug khaws cia, tab sis lub zog kinetic tsis yog. Hauv kev sib tsoo tsis ywj pheej tag nrho, cov khoom lo ua ke tom qab kev sib tsoo.
- Yuav ua li cas thiaj li khaws tau lub zog thaum muaj kev sib tsoo, txawm tias nws yog elastic lossis inelastic?
- teb: Lub zog tseem khaws cia hauv kev sib tsoo vim yog Newton txoj cai thib peb, uas hais tias rau txhua qhov kev nqis tes ua, muaj kev sib npaug thiab sib txawv. Tag nrho lub zog ntawm lub kaw lus ua ntej kev sib tsoo yog sib npaug rau tag nrho lub zog tom qab kev sib tsoo.
- Vim li cas lub zog kinetic tsis ib txwm khaws cia hauv kev sib tsoo?
- teb: Lub zog kinetic tsis raug khaws cia rau hauv kev sib tsoo inelastic vim tias qee qhov ntawm lub zog kinetic thawj zaug raug hloov mus rau lwm hom zog, xws li suab, cua sov, lossis kev hloov pauv ntawm cov khoom.
- Lub zog tag nrho ntawm ib lub cev puas hloov pauv tau thaum muaj kev sib tsoo? Yog tias muaj, yuav ua li cas?
- teb: Yog, tag nrho lub zog mechanical tuaj yeem hloov pauv thaum lub sijhawm sib tsoo tsis sib luag. Txawm hais tias tag nrho lub zog mechanical (kinetic ntxiv rau lub zog) raug khaws cia rau hauv ib lub kaw lus cais, hauv kev sib tsoo tsis sib luag, qee lub zog kinetic yuav raug hloov mus ua cov ntawv tsis yog mechanical xws li cua sov lossis suab.
- Yuav ua li cas ib tug neeg thiaj li paub seb qhov kev sib tsoo puas yog elastic lossis inelastic tsuas yog los ntawm kev soj ntsuam cov khoom ua ntej thiab tom qab kev sib tsoo?
- teb: Yog tias cov khoom sib tsoo thiab lub zog kinetic tag nrho ua ntej kev sib tsoo sib npaug rau lub zog kinetic tag nrho tom qab kev sib tsoo, nws yog kev sib tsoo elastic. Yog tias cov khoom lo ua ke lossis lub zog kinetic tag nrho txo qis, nws yog kev sib tsoo inelastic.
- Lub luag haujlwm ntawm tus coefficient of restitution hauv kev tshuaj xyuas kev sib tsoo yog dab tsi?
- teb: Tus coefficient ntawm kev them rov qab (feem ntau yog qhia los ntawm ) yog ib qho kev ntsuas seb qhov kev sib tsoo "bouncy" npaum li cas. Nws yog txhais tias yog qhov ceev ntawm kev sib cais faib los ntawm qhov ceev ntawm kev mus txog. Rau qhov kev sib tsoo elastic zoo meej, , thiab rau qhov kev sib tsoo tsis sib luag zoo kawg nkaus, .
- Kev txuag ntawm lub zog angular siv rau kev sib tsoo li cas?
- teb: Thaum muaj kev sib tsoo uas tsis muaj lub zog sab nraud ua rau lub cev, lub zog ntawm lub kaum sab xis tseem khaws cia. Qhov no siv tau rau cov khoom uas tig thiab sib tsoo lossis rau cov xwm txheej zoo li cov neeg caij skating rub lawv txhais tes kom tig sai dua.
- Vim li cas kev sib tsoo hauv ntiaj teb tiag tiag feem ntau zoo li tsis muaj zog?
- teb: Feem ntau kev sib tsoo hauv ntiaj teb tiag tiag yuav ua rau lub zog kinetic poob rau suab, cua sov, lossis kev hloov pauv. Cov kev hloov pauv zog no ua rau feem ntau ntawm kev sib tsoo hauv ntiaj teb tiag tiag tsis ruaj khov rau qee qib.
- Hauv kev sib tsoo ib-seem ntawm ob yam khoom uas muaj tib lub cev hnyav, ua li cas rau lawv qhov ceev tom qab kev sib tsoo?
- teb: Hauv kev sib tsoo uas muaj ib qho ntev thiab ywj pheej ntawm ob yam khoom uas muaj qhov hnyav sib npaug, lawv qhov ceev tsuas yog hloov tom qab kev sib tsoo. Yam khoom 1 xaus nrog qhov ceev pib ntawm Yam khoom 2, thiab rov qab los.
- Ob yam khoom puas tuaj yeem lo ua ke hauv kev sib tsoo uas ywj pheej?
- teb: Tsis yog, yog tias ob yam khoom lo ua ke, qhov kev sib tsoo yuav tsis sib zog kiag li. Hauv kev sib tsoo uas sib zog, cov khoom yuav tsum rov qab los ntawm ib leeg, thiab tag nrho lub zog kinetic yuav tsum tau khaws cia.
